Generally, fluid passages, through which fluid passes for lubrication or cooling, or to operate a variable valve timing device, are formed in the cylinder block and the cylinder head of an engine. Most fluid passages having the above-mentioned functions are formed through a separate drilling process after the cylinder block and the cylinder head have been made through casting.
Therefore, to ensure watertightness of the fluid passages formed in the cylinder block and the cylinder head through the drilling process, a passage closing operation must be performed after the drilling process. The closing operation is implemented by press-fitting a closing member, such as a tapered plug or a steel ball, into the inlet of each of the fluid passages formed in the cylinder block and the cylinder head.
The operation of closing the inlet of the fluid passage through the press-fitting process must be implemented several times even in one cylinder block or cylinder head. Thus, in consideration of productivity, an automated rather than manual process is preferred. In particular, an automatic press-fitting apparatus using a robot can be preferred.
An automatic press-fitting apparatus can be required to accommodate to a flexible manufacturing system (FMS) which is in use and in which a variety of vehicle models is manufactured in a single assembly line.
The information set forth in this Background of the Invention section is only for enhancement of understanding of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.